This study is aimed at providing data on the effects of child spacing and family size on mental health (coping ability) so that each American can make an informed judgment regarding the quality of individuals produced by various family sizes, and sibling age-gap, and sex of adjacent siblings. Subjects to be studied are 250 VAH patients; 500 brothers, 300 sisters and 500 parents of VAH patients, 150 college-going veterans, 500 inner-city families, parents and children; 100 adolescent patients, Buffalo State Hospital; 200 sibs of BSH patients; 100 learning-behavior- disorder children; 200 sibs of lbd children; 100 patients Children's Psychiatric Center, 200 sibs of CPC; 1400 Cleveland Psychiatric Institute patients; 2674 Postgraduate Center for Mental Health patients, 200 PCMH lesbian patients and 200 controls; and 1076 college entrants of 1958. Careful sampling will hold experimentally constant race, sex, ordinal position among sibs, age, family size, intactness of family, social class, urbanness, and sex of close sib. Personality development and level of coping will be measured by the MMPI and by scaled life- history facts yielding level of functioning in vocational, academic, marital, social, and law-conforming areas. Multi- and univariate F ratios at p .05 will determine the scales characteristic of each family- constellation position. An annotated, classified, indexed bibliography of 750 articles on family constellation and its correlatives will be prepared. In addition to normative data on sib-gap and family size resulting from this experiment, the statistics amassed in the census of the United States on these factors will be scrutinized and presented in form of comparative norms.